1. Field of the Invention
The present invention relates to a carbonizing furnace for carbonizing combustibles.
2. Description of the Background Art
Conventionally, in the case of charcoal making, for example, combustible raw materials are accommodated in a closed charcoal kiln. In the charcoal kiln, gas elements of the raw materials are removed by burning. In a closed carbonizing furnace, the amount of oxygen is limited, so that carbides can be prevented from over burning and forming into ash. Further, the temperature in the furnace can be maintained at a high level, so the gas elements can be removed from the hearts of the raw materials. Thus the carbides can be made efficiently.
The inventor invented a method of making a carbide (Japanese Patent Kokai Gazette No. 8-208209), in which a combustible raw material can be carbonized in an oxidizing atmosphere without burning out if the surface of the raw material is coated with an inorganic binder, e.g. bentonite. The inventor supposes that the oxidization of the raw material is limited by the inorganic binder. In the case of coating the raw material with the inorganic binder and a water-soluble sugar, the oxidization is more effectively limited. To coat the surface of the raw material, the inorganic binder and the water-soluble sugar may be mixed with water.
The conventional closed carbonizing furnace is effective for carbonizing bigger materials, e.g., wood. However, it takes a long time to carbonize them because the materials must be accommodate in the furnace. Therefore, the conventional closed carbonizing furnace cannot be employed for industrial use or mass production. Further, the temperature in the furnace must be high because the gas elements are burnt out therein, so the inner walls of the furnace must be formed with heat-resisting materials, e.g., ceramics. By employing the heat-resisting materials, manufacturing cost and maintenance cost of the furnace are increased.